Alternating current commutator motor



Feb. 27, 1940. A. s. NoRcRoss ALTERNATING .CURRENT COMMUTATOR MOTORFiled Aug. so. 1937 5 sheets-sheet x C. L i

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Filed Aug. 30, 1937 5 Sheets-Sheet 4 0F MAX/MUM .ST/woe Vom-AGE so e7'4o e5 50 @9143 I 2o lo 0 I 2 me/moneys .SPEED LLl/H/ Feb. 27, 1940. A.s. NoRcRoss v ALTERNATING CURRENT COMMUTATOR MOTOR Filed Aug. so. 19:575 sheets-sheet 5 vMiel @ig/li Patented Feb. 27, 1940 UNITED STATESPATENT OFFICE ALTERNATING CURRENT COMMUTATOR MOTO 24 Claims).

My invention, relates to a novel type of motor design for improving thecommutation and power factor of alternating current commutator motors.While the principles of my invention are I particularly applicable tothe single-phase motor described in my former Patent No. 2,060,106,loperating either as an adjustable or as aconstant speed motor, they are'also applicable to polyphase or other types of commutator motors.

In allalternating current commutator motors there is a transformervoltage induced into the coils undergoing commutation. This objectionaltransformer voltage is in some cases almost completely neutralized by aspeed voltage at 1I. synchronous speed. However, as the speed deated asa constant speed motor having good commutation at a speed differinggreatly from a0 synchronism. Thus for example, by operating a two-polemotor considerably above synchronous speed, a very high speed motor maybe obtained which has shunt `speed characteristics and good commutation.

As an improvement on the type of single-phase motor shown in my formerPatent No.l 2,060,106,

I adjust the voltage'impressed upon the main and quadrature windings asdescribed in said patent to obtain wide variations in speed, and 40 inorder to further increase the speed range, I vary the voltage impressedupon the armature winding. In order to provide desirablecharacteristics, particularly good commutation', over a.. wide speedrange, I determined after much study that a motor constructed to operatein-accordance with two definite formulas, whichwill be set forth later,would provide these desirable characteristics and then I determined thatpossible ways of keeping these equations both vsatisfied for differentspeeds would be to vary the different factors thereof in accordance withcertain curves. I then designed avoltage regulator or controlling devicewhich would supply voltages to the stator windings and 'armature windingin Such predetermined combinations varying for (ci. 17e-ziel differentspeeds in accordance with said curves as to cause the speed andtransformer voltages induced into the armature coils undergoingcommutation to be substantially equal atv all speeds.

Then it became merely a matter, if ,it-be'desired sf to design aconstant speed motor to operate at a speed differinggreatly fromsynchronism, of So arranging and connecting the windings that they wouldsatisfy these two equations.

A further objectk ofmy invention is not only l. to design a motor in`accordance with said equations which will operate over a wide range ofspeeds with improved commutation characteristics, but also'to provide incombination therewith means to provide in the rotor a power ll factorimproving component of voltage as well as to improve the power factorthereof. In the single-phase motor shown in my former patent,

-it is apparent that the capacitor itself provides means to provide inthe rotor a power factor' N improving component of voltage. Employing myinvention, however, in a polyphase motor, I preferably employ a meansfor improving the powerI factor easier to install and less expensivethan a capacitor for each phase, preferably compris- 2l ing power factorcoils suitably connected in each rotor vcircuit and preferably energizedfrom other phases. I'he power factor may also be improved by displacingthe brushes from the axis of their respective stator windings. By usingthe power 30 factor coils and by properly locating the brushesconjointly, I am able to ,maintain va. high power factor andconsequently high torque per ampere throughout a wide speed-range.

Further features of my invention relate to 35 improvements in variousspecific structures for carrying out the principles thereof.

These and such other objects of my invention as may hereinafter appearmay be best understood from a description of the accompanying 40drawings which illustrate various embodiments thereof.

In the drawings,

Fig. 1 is a circuit diagramof a single-phase ladjustable speed motorofthe typevdescribed in 45 my former Patent No. l2,060,106,1modif-led inaccordance with my invention so that the armature may be adjustablyconnected to the autotransformer in order that the voltage impressedupon 'the armature circuit may be adjusted in- 50 stead of having thearmature short-circuited as shown in said patent with the voltagesimpressed upon the main winding and the quadrature winding eachbeing'independently adjustable.

Fig. 2 is a circuit diagram of the single-phase l adjustable speed motorshown in Fig. 1 modified so as to have the same voltage adjustablyimpressed upon both the main and quadrature windings.

Fig. 3 is a circuit diagram ofa constant speed motor constructed inaccordance with my invention.

Fig. 4 is a vector diagram showing approximately the phase relations ofthev speed and transformer voltages induced into the coils undergoingcommutation in v all types of single- Dhase motors shown in Figs. 1, 2and 3.

Fig. 5 is a graph showing a particular manner in which the voltagvimpressed upon the main, quadrature and amature windings of thesingle-phase motor shown in Fig. 1 may be adjusted in accordance withthe curves shown therein to improve the commutation over a large speedrange. the curves being determined on the basis of-a constant torquebelow synchronous speed, I as lshown therein, and .onv the basis-of aconstant horse power above synchronous speed.

Fig. 6 is a graph showing a particular manne in which the voltagesimpressedl upon the stator windings.. including both the main andquadrature windings of the single-phase motor shown in Fig. 2 and theamature winding thereof may be adjusted to improve the commutation overa large speed range, the curves being determined on the basis of aconstant torque. below synchronous speed, I as shown therein, and on thebasis of Va constant horse power above synchronous Fig. 'I is a verticalsectional view taken through a suitable voltage regulator for supplyingseparatejvoltages to the main winding, tquadratu're winding and armaturewinding of the embodiment of my invention shown in Fig. l, adjustable tovary saidimpressed voltages in accordance with the graph shown in Fig.5.

Fig. 8 is across sectional view taken along the line l-l of Fig. '1.

` Fig. 9 is a vertical sectional view taken through a suitable voltageregulator for supplying voltages to the stator windings, including themain and quadrature windings of the embodiment of my invention'shown inFig. 2 and the armature winding thereof. adjustable to vary saidimpressed voltages in accordance with the graph shown inldg'.' 8.

Fig. 10 is across sectional view taken along the line Il-iI of Ii'ig. 9.

Fig. 111s a circuit diagram of a three-phase adjustable speed motorconstructed in accordance with my invention employing,` however, powerfactor` coils as the speciiic embodiment of means to provide in therotor a power factor improving component of voltage.

Fig. 12 is a vector diagram showing approximately the phaseL relationsof the speed and transformer voltages induced into the coils undergoingcommutation in the polyphase motor shown in Fig. 11, being substantiallysimilar to the vector diagram shown in Fig. 4 for the various types ofsingle-phase motors shown herein.

Fig. 13 is a graph showing a particular mannerr` in which the voltagesimpressed upon the stator windings and armature windings of thepolyphase motor shown in Fig. 11 may be adjusted to improve thecommutation over a large speed range, and being generally similar to thegraph shown in Fig. 6 for the types of single-phase motors shown herein,the curves being determined on the basis of aconstant torque belowsynchronous speed, l as shown therein, andon thebasis of a constanthorsepower above synchronous speed.

Fig. 14 is a vertical sectional 'view taken through a suitable voltageregulator, comprising three superimposed rings of the type shown inFigs. 9 and 10, one for each phase, rigidly mounted on a single shaft tobe controlled by a single out, Figs. 1-.10 illustrate variousembodiments of single-phase motors constructed in accordance with theprinciples of my invention, whereas Figs. l1-15 illustrate my inventionapplied to a three- ,phase motor.

i The different embodiments of single-.phase alternating current motorsshown in Figs. 1-10 are in most respects modifications of thesingle-phase motor described and claimed in my former P atent. No.2,060,106. In general the embodiments of my invention shown in Figs.1-10 are constructed and operate in similar fashion to the embodimentsof my invention shown in said patent. If a fullerhdescriptipn of thetheory of such a motor be ,desired than set forth herein, including theequations' and symbols involved, reference is hereby made to saidpatent.

In the structure shown in Fig. 2 of said patent, I have providedadjustable means to supply voltage to the main stator winding andadjustable means to supply voltage to the quadrature winding. In thestructure shown in said patent, however, the armaturel is permanentlyshort-circuited. In order to improve the commutation throughout and toprovide a greater speed range,

I so modify the structure shown in my former .patent as to adjustablyvary the voltage also supplied to the armature winding. Instead ofshort-circuiting the armature A, I adjustably connect the `armature tothe auto-transformer T shown in4 Fig. 1 or to the transformer T shown inFig. 2 to receive an adjustable voltage therefrom. In the type ofsingle-phase alternating` current motors shown in Figs. 1-3, I haveemployed and shown diagrammatically a motor with a main stator windingembodying a main coil M,

which fonconvenience may be denominated the main coll or winding/ Asecond or quadrature winding Q is located in quadrature or at ninetyelectrical degrees apart from said main winding. In other words, the4coils M and Q are in space quadrature. For convenience, I will refertothe v winding Q as the quadrature winding and to the windings M and Qtogether, namely the main and quadrature, as the stator windings.

In the particular embodiment shown in Fig. 1.

voltage is impressed from-the main line 20 or source of supply onto theauto-transformer T, where in turn it is impressed upon the main windingM and the quadrature winding Q as shown in said patent. By adjusting thepositions of the riders MR and QR for the main winding and thequadrature winding on the auto-transformer shown in Fig. 1 or the singlerider (M +Q R on the transformer shown in Fig. 2, the voltages impressedupon the main and quadrature wind- -ings may be varied as shown in saidpatent. As

also shown in said'patent, I provide means to `provide in the rotor apower factor improving 1l.

' component of voltage comprising the capacitor C connected in thequadrature field circuit. As stated in said patent, the capacitor C, inaddition to improving the power factor, improves the torque, commutationand other desirable characteristics of the motor.

The armature A rotates Within'the stator and is provided with acommutator having brushes B. Instead, however, of short-circuiting thearmature as shown in said patent. I adjustably impress voltage upon thearmature winding from the transformer or auto-transformer T by means oi'adjustably moving the supplemental rider AR relative to said transformeror auto-transformer. I have found in practice that by supplementallyadjustably impressing or varying the voltage impressed upon the armaturewinding, I am enabled to increase the speed range and in general improvethe operating characteristics of the motor. i

The speed of this motor may be adjusted by controlling ou and po asdescribed in the above- .mentioned patent, or by controlling the voltageVA impressed upon the brushes. The voltage VA is substantiallyinphase-with Ewr above synchronous speed and in phase opposition to itbelow synchronous speed. It will be observed by referring to Fig. 3 ofthe above-mentioned patent that adding a voltage VA in phase with Emwiliresult in an increase in Eqs-and a corresponding increase in speed.Similarly adding a voltage VA in phase opposition to Em will decreaseEQs and the speed. Inasmuch as Vu and VQ vary in proportion to qm andoo. the speed of this motor may therefore be adjusted by controlling anyonev or all three of the variables Vu, VQ and VA, and may beapproximately expressed by the following algebraicequation:

where Z is the impedance of the armature circuit,

' In equals the armature current. This expression assumes that Eqs is inphase opposition to Em' which is substantially the case as Eqs is onlyslightly displaced from this position to vimprove the performance of themotor.

A.'I'he resultant voltage induced 'intothe coil undergoing commutationmust 'be small to prevent brusli sparking and excessive losses ldue toshown by Fig. 4 so that the best commutation is Therefore, in adjustingthe speed of the abovementionedsingle-phase motor in accordance withEquation A1, it isadvisable to adjust the controlling factors ou, o andVA in such a manner as to approximately satisfy Equation 2. Furthermore,it is possible to adjust the quantities qm, pq and VA in such a way asto satisfy Equations 1 and 2 and at the same time maintain particularhorsepower or torque characteristics. For instance, by adjusting pqinversely proportional to the speed, the motor will be inherently aconstant horsepower motor, while if po is maintained constant the motorwill be inherently a constant torque motor.

In some cases it may not be practical to keep et and e. exactly equalthroughout the entire speed range. For example in Fig. 5, Vu, VQ and VAare adjusted to ysatisfy Equation 2 and maintain constant horse-powercharacteristics only above synchronous speed. To maintain the samehorsepower characteristics and keep es equal to et below synchronousspeed, excessive main and quadrature field fluxes would be required ifthe field fluxes were normal at synchronous speed. Under this conditionit might be advisable to obtain the speeds below synchronism bykeepingVu and VQ constant and adjusting VA as indicated in Fig. 5. -While e. isnot exactly equal to et when this is done, the resultant voltage inducedinto the coil undergoing commutation is small for speeds fromsynchronous to one-half synchronous speed. Constant torquecharacteristics will then be obtained below synchronous speed.

There are other cases where it may not be practical to maintain e.exactly equal to es throughout the speed range. For example, if Vu iskept equal to VQ as indicated in Fig. 6, the auto-transformer isobviously simplified and the small diierence between e. and et in thiscase will not produce appreciable brush sparking throughout a largespeed range.

The two component voltages et and-8| will be exactly in phase oppositionwhen the two fields pn and pq are in exact time quadrature. In this casethe two oscillating fields are in both space and time quadrature andwhen they are equal a circular revolving field results which isidentical with that obtained from a polyphase machine. It thereforeshould be evident that commutation in a polyphase motor is equivalent tothat of a single-phase motor when the main and quadrature fields areequal and in time quadrature.

The conditions of Fig. 6 therefore are applicable to a polyphase motorwhere the voltages indicated are phase voltages as shown in Fig. 13. Bymeans of a circuit arrangement, such as indicated in Fig. 1l, the speedof a three-phase commutator motor may be adjusted by controlling thevoltages impressed upon the stator and armature brushes in such a manneras to keep the difference between e. and et small and thus maintain verygood commutation over' a large speed range.

Figs. 5 and 6 represent graphs of suitable ways to satisfy the'Equations41 and 2 in the manner hitherto explained. To obtain these curves fromEquation 1 the term LZ drop 'will obviously not be the same fordifferent motors and those skilled in the art can modify thesecurves totake intol consideration the voltage drop for any particular motor. Aswill be apparent from an inspection of Figs. 1 and 5, there are threevariables, namely l I have shown in Fig. 1 riders Vu, VQ and VA. o MR,QR and AR to adjustably contact the autotransformer T to provideindependent variation of each of these three variables. It is apparentthat if a voltage regulator be provided which will supply voltages toeach of the stator windings,

including the main winding and quadraturel speed and transformer.voltages induced into the coils undergoing commutation will besubstantially equal at all speeds.

in Fig. 2 and the vsmall difference between e. and

et in this case willnot produce appreciable'brush sparking throughout alarge speed range.

I have shown .in Fig. 6 a graph of suitable' curves to satisfy the twoabove equations with and quadraturey maintained equal. `With the threeseparately impressed voltages as shown in Fig. l, thel speed andtransformer voltages induced into the coils undergoing commutation willbe practically equall at all speeds as shown in the table later setforth.4 If, however, the same voltage be impressed upon the main windingand quadrature winding, the speed and transformer voltages induced intothe coils undergoing commutation will vary slightly as shown in case 5in said table. but for all practical pur.

poses. as compared to all former types of motors, will besubstantiallyequal to provide the desirable oommutationcharacteristicsof my invention. I

therefore employ the words "practically equal' in the claims to satisfycase 4 of said table as attained in the embodiment shown in Figs. 1 and5 of the drawings. I employ the words substantially equal to includecase 5 shown in said table as' attained in the embodiment shown in Fils.L2 and 6 ofthe drawings. it is also apparent that by impressing the samevoltage on the main and quadrature windings a much simpler voltageregulator maybe provided which may be designed to act only for twoinstead of three variables. I have shown inll'igs. 9 and 10 such asimplified voltage regulator which I will also describe in more detaillater. v

It is also apparent that instead of providing adjustable riders to varythe voltages impressed upon the armature, main and quadrature windings,either jointly lor independently, said respective windings may bearranged and connected to the supply in such a predetermined combinationas to cause the speed and transformer voltages induced into the coilsundergoing commutation to be substantially equal at any speed above orbelow synchronism. This maybe done by permanently fitting the adjustableriders against thedesiredpoints in the desired predetermined combinationof a transformer or auto-transformer, in accordance with the curvesshown in Fig. 5 or 6, or otherwise in accordance with said equations,

or it may bedone by varying the general design of the motor to cause itto operate in accordance with said equations. I have shown in Fig. 3 aconstant speed vrnotor constructed in accordance with my invention, withthe desired number of turns in the respective main, quadrature andarmature windings to satisfy said equations.

As stated hitherto, my invention is also applicable to a polyphase motorand I have shown 'in Fig. 11 a three-phase motor constructed inaccordance with my invention. In such a motor there is provided a rotorA having a commutator armature winding, a stator having a separatestator lwinding M for each phase and a pair of brushes in contact withsaid commutator for each phase. In a polyphase motor of this descriptiona quadrature winding is not necessary in order to produce the desiredamount of torque, the

desired amount of torque being provided by the relationship andconnections loi the respective also includes et and es.

adjust the voltage supplied to the stator windings' M of each phase by,`means of riders MR in contact with the respective transformer T of eachphase and I adjust the voltage supplied to said armature winding of eachphase by means of l riders AR also in contact with each respective thevoltages impressed upon the main winding transformer. I have shown inFigs. 14 and 15 a suitable voltage regulator to conjointly supplyAvoltages t said stator and amature windings circuit a power factorimproving component of voltage. In place of employing an expensivecapacitor for this purpose, however, in the preferred embodiment shown Iprovide thepower factor coils C in each rotor circuit which may bereadily 'energized from other phases as shown.

Furthermore, by displacing the brushes B|,BI,

B2, B2 and B3, B3 for the respective phases from the axis of theirrespective stator windings,l I may supplementally improve the powerfactor.

-The magnitude of the power factor improving component 'derived fromsaid power factor improving coils and the power factor improvingcomponent of voltage derived bydisplacing the brushes is dependent uponthe design of the motor and thespeeds desired. It is evident that ingeneral high power factor and high torque per ampere are inseparable andit is understood that the said means for producing a high power factorwill -also produce high torque per ampere because of the favorable phaserelation between the armature currents and the torque-producing fluxes.The upper portion of the diagram shown in Fig'. 1l diagrammaticallyillustrates the control which may comprise a linear transformer asdiagrammatically illustrated therein having the adjustable riders AR.for regulating the voltage impressed through the armature winding AW foreach phase, or each respective transformer T may comprise a ringauto-transformer as shown in Figs. 14 and 15.

'Ihe revolvingfield set up by a polyphase motor is equivalent to a fieldproduced by two oscillating fields 4m and pq which are equal and in timeand space quadrature and thus may be represented by avector diagram, asshownin Fig. 12, which This diagram is the same as that for asingle-phase motor with the quadrature Winding equal to and in time andspace quadrature with the main winding.

Therefore, M and do may be considered to exist in the armature whetherproduced by the main and quadrature windings of the singlephase motor orby the combined effect of the stator phase windings of a polyphasemotor. However, in a polyphase motor en and Q are equal and in time andspace quadrature, while in a single-phase motor par and Q ymay beunequal and not in exact quadrature as explained herein. It is`understood, therefore, that 4m and pq used in Equation 1 are produced bythe comadjustable riders 'MR for regulating the voltage l impressedthrough the main winding nMW and aroaoso bined effect of the statorlwindings and that they are equal and in time and space quadrature in apolyphase motor.

Figs. '7-10 and 14-15 illustrate different voltagey regulators which maybe' employed for adjusting the voltages impressed upon the variouswindings by-a unitary control.v Such regulators can be designed tosupply adjustable voltages in any desired manner, such forfexample asare illustrated in Figs. 5 and 6. However, it may be practical for someyapplications to use a simpler'controller using a system of links orgears which will approximate the voltage relations that may beobtainedfrom the regulator. It is possible that linear voltage characteristicsapproximating voltage relations such as illustrated in Figs. 5 and 6will in some cases be satisfactory and if such is the case, thecontroller is obviously simpliiied.

I have shown in Figs. 7 and 8 and diagrammatically illustrated in theupper portions of Figs. l and 2 a suitable type of voltage regulator. toadjust the positions of the respective riders AR, MR and QR, separatelyand independently. relative to the transformer winding TW spirally woundaround the transformer core TC to supply separate voltages to said mainwinding, quadrature winding and armature winding to satisfy saidequations, or in such predetermined combinations varying for differentspeeds as to cause the speed and transformer voltages induced into thecoils undergoing commutation to be substantially equal at all speeds inaccordance with the respective armature`voltage curve.. main fleldvoltage curve, and quadrature field voltage curve shown in Fig. 5. Forthis purpose the tra-nsformer T, in place of being linear asdiagrammatically illustrated in Figs. 1 and 2, is made in the form of aring rigidly mounted in the bottom of a casing and I mount a shaft 24concentric with the center of the ring having a plurality ofindependently' rotatable collars AC, QC and MC loosely mounted insuperimposed relationship thereon.` Each collar is provided with arespective gear AG, QG and MG and has' a respective arm dependingtherefrom adapted to carry the respective riders AR, QR and MR torespectively contact the transformer winding'on the transformer core TC.In the embodiment shown. the quadrature windingrider QR is adapted tocontact the interior of the transformer core TC and the main rider MRand armature rider AR are adapted to contact respectivelythe exterior ofsaid ring. A separate'shaft 28 is independently mounted within theregulator box 28 and has rigidly mounted thereonthe respective camsprovided with the respective cam slots MS,` main slot, QS,

quadrature slot and AS, armature slot in the same superimposedrelationship as the respective main collar MC, quadrature collar QC andarmature collar AC are mounted on the shaft 24. A

thereof with respective gear segments dapted to mesh with and actuatethe respective gears MG, QG, and AG on the respective collars MC, QC,

and AC to actuate the respective riders MR, QR y and AR relative to thetransformer winding TW.

'I'he upper end of the shaft is provided with the turning handle 32. Thecam slots MS, vQS and AS are constructed exactly in accordance with therespective main voltage curve, quadrature voltage curve and armaturevoltage curve shown in Fig. 5. It is thus-obvious that on rotation ofthe handle 32, the respective cams will be rotated vso that therespective pins will ride in the re- 'cordance with the graph shown inFig. 6 to simultaneously vary the voltages supplied to the statorwindings and the armature winding substantially in accordance with thetwo equations and in -such predetermined combinations varying fordifferent speeds as to cause the speed and transformer voltages inducedinto the coils undergoing commutation to be substantially equal at allspeeds. As hitherto explained, in accordance with the graph shown inFig. 6, I supply at all speeds equal voltages to the main and quadraturewindings so that only one voltage curve is required for the differentspeeds. In place, therefore, of constructing diiferent cams to regulatethe movements oftwo different riders in accordance with differentcurves, I mount the respective riders (M+Q)R and AR diametrically of thering T, and I arrange the respective windings (M -l-Q) W and AW on thetransformer core TC, such as by varying the spacings and number of theturns or otherwise in accordance with their respective curves. Inasmuchas the percentage in the transformer box 28. I provid.: a shaft uextending through the cover of the box having a diametric yoke YVmounted thereon having arms depending therefrom adapted to carry therespective riders AR and (M-l-Q)R to contact the respective windings AWapd (M+-Q) W diametrically of said ring on rotation of the handle 32mounted onv the upper end of said shaft I4,

I have shown in Figs. 14 and 15 a suitable type of control means for thepolyphase motor shown in Fig. 11. Inasmuch as the respective riders MRandAR on the respective transformers TI, T2 and T3 for the threedifferent phases may be adjusted simultaneously in accordance with thecurves shown in Fig. 13, which as stated-are similar to the curvesshown'in Fig. 6, a plurality of the control means shown in Figs. 9 and10, which operate in accordance with the curves shown in Fig. 6 may besuperimposed one upon each other for each transformer TI, T2 and T2 foreach respective phase. Thus l the respectivetransformer cores TCI, TG2and TCI are superimposed one 'above the other and a plurality of yokesYI, Y2 and YI are rigidly mounted in the desired superimposed spacedrelationship on the shaft I4 rotated in similar fashion as in Figs. 9and 10 by the handle I2 to carry respectively and operate the-respective riders MRI and ARI, MR2 and ARI, and MRI and ARJrespectively in equal diametric relationship in contact with therespective armature and main windings AWI and MWI, AW2 and NW2, and AWSand MWl on the respective transformer cores TCI, T02 and TCS. Therespective windings on each core are similar to the windings hithertodescribed in Figs. 9 and 10 to satisfy the curves shown in Figs. 6 and13. The respective power factor coils c in each rotor circuit are shownin Fig. 15 mounted adjacent one end .of each respective amature winding.

In order that the advantages of my invention may be better understood,the following table is given to illustrate the degree oi neutralizationthat may be realized for a few particular speeds obtained by nvedifferent methods of adjusting the motor speed.

.Table Commutation voltages for diiller` entspeedsex ressedin numberMethod of speed control f um Y nous Wed Cae'e 1.-The speed is u- 1 1 1 1adjusted by varying t.- .25 1 4 D l with VA-o and u-c.- 76 o 3 8 'oconstant.

Can .tf-The speed is e.- 2 l .6 .33

adjusted by varying .B i 2 3 pq with VA-O Ind 1.5 0 1.5 2.8 Qu constant.

Can 3.--Tha speed is nl i 1 1 adjusted by varying c.- 1 2 3 VA with both.mand n-e.- o 1 2 9o constant.

Gau .tf-The speed is anl l .5 .33 adjusted Il in h- .5 l 6 33 ig. 5.eq-h- 5 0 0 Can 6.--The speed is nl 1 .5 .33

adlusied as .5 l 1 in Figs. 6 and 13 (or .5 0 .5 .66 single or threephase motors respectively.

The magnitudes of the coil voltages involved are of course dependentupon the design of the motor. However, the transformer voltage inducedinto the coil undergoing commutation at synchronous speed is forconvenience termed normal and expressed as unity and the resultant andcomponent transformer and speed voltages are expressed as a decimal partof this normal voltage. The principles of this invention are used inCases 4 and 5 where it will be observed that the resultant commutationvoltages are much lower than in the Cases 1, 2 and 3 where theprinciples are not used.

Cases l and 5 are only to illustrate two particular combinations vwhichutilize the basic idea of adjusting the voltages impressed upon the var.ious circuits in combinations that will give the desired speeds and atthe same time neutralize the transformer commutation coil voltage with aspeed voltage adjusted to have substantially the same magnitude.

It should be obvious that these principles are `applicable in many otherforms for adjustable speed motors and are also useful for vconstantspeed motors. For example, a very high constant speed motor may beobtained by operating a two-pole motor at a speed considerably greaterthan synchronism. In such a case the transformer may be entirelyeliminated as in Fig. 3.

This motor is particularly suitable for high speeds greater than 3600 R.P. M. y

It is thus apparent that I have provided a con.-

trol for an alternating current motor, whether it be of single orpolyphase type, which may be either operated as an adjustable speedmotor having the desired characteristics over a wider range of speedsthan hitherto thought possible or which may be .operated as a constantspeed motor to operate in accordance with the principles of my inventionand which may, if desired, be provided in combination therewith withmeans to provide in the rotor a power factor improving component ofvoltage and having the advantages explained above.

For convenience, I append a list of the symbols used in thissp'eciilcation in referring to the various electric forces considered.

It is understood that my invention isv not limited to the specificembodiments illustrated herein and that various deviations may be madetherefrom without departing from the spirit andscope of 'the appendedclaims.

What I claim is:

l. In combination, an alternating current motor comprising statorwindings, a rotor having a coiled commutator armature winding, brushesin contact with said commutator, means to provide in the rotor a powerfactor improving component of voltage, and a voltage regulatorconnectable to a supply, comprising magnetic core means, winding meanswound around said core means connectable to said supply, a plurality ofcooperating power transmitting means, each individually connected to oneof said stator windings or said armature winding and each mounted toindividually move in respect to said core means and each capable ofproviding an independent variable voltage and unitary control means forsimultaneously relatively moving the adjustable power transmitting meansonly in such a predetermined manner as to provide independent variablevoltages in accordance with predetermined voltage and speedcharacteristics varying for different speeds as to cause the speed andtransformer voltages induced into the coilsundergoing commutation to besubstantially equal at all speeds. y

2. In combination, an alternating current motor comprising statorwindings, a rotor having a coiled commutator armature winding, brushesin contact with said commutator, and a voltage regulator connectable toa supply, comprising magnetic core means, winding means wound aroundsaid core means connectable to said supply, a

plurality of cooperating power transmitting means, each individuallyconnected to one of said stator windings or-said armature winding andeach mounted to individually move in respect toA said core means andeach capable of providing an independent variable voltage and unitarycontrol means for simultaneously relatively moving the adjustable powertransmitting means only in such a predetermined manner as to provideindependent variable voltages in accordance with predetermined voltageand speed characteristics varying for different speeds as to cause thespeed and transformer voltages induced into the coils undergoingcommutation to be substantially equal lals at all speeds.

3. In combination, an alternating current motor comprising a mainwinding, a rotor having a coiled commutator armature winding, brusheslplaced substantially along the axis of said main winding, a quadraturewinding spaced ninety electrical degrees from the main winding,dephasing means in the circuit oi the said quadrature winding comprisinga capacitor of such'magnitudeas to dephase the circuit of the quadraturewinding relative tothat of the. main winding by an amount to produce anangle having a cosine between .5' and l between the armature current andthe quadrature field flux and a voltage regulator connectable to asupply, comprising magnetic coremeans,wind ing means wound around saidcore means connectable to said supply, a plurality oi' cooperatingpowertransmitting rider means, each individually com nected to the mainwinding, quadrature winding or armature winding and each mounted toindividually move in respect to said core means in continuous contactwith said winding means and each capable of providing an independentvariable voltage and unitary control means for simultaneouslyrelatively, moving the adjustable rider means only in such apredetermined manner so as to provide independent variable voltages inaccordance with predetermined voltage and speed characteristics varyingfor diierent speeds as to cause the speed and transformer voltagesinduced into the coils undergoing commutation tobe substantially equalat all speeds.

4. In combination, an alternating current motor comprising a mainwinding, a rotor having a coiled commutatorarmaturewinding,brushesplacedsubstantially along the axis of said mainwinding, a

quadrature winding spaced ninety electrical degrees from the mainwinding, means for dephasing the current in said quadrature winding toproduce an angle having a cosine between, .5 and 1 between the armaturecurrent and the quadrature field ilux and a voltage regulatorconnectable to a supply, comprising magnetic core means, windingmeanswound around said core means connectable to said supply, aplurality of cooperating power transmitting rider means, eachindividually connected to the main winding, quad-` rature winding orarmature winding and each mounted to individually move in respect tosaid core means in continuous contact with said winding means and eachcapable of providing an independent variable voltage and unitary controlmeans for simultaneously relatively moving the adjustable rider meansonly in such a predetermined manner so as to provide independentvariable voltages in laccordance with predetermined voltage and yspeedcharacteristics varying for different speeds as to cause the speed andtransformer voltages induced into the coils undergoing .commutation tobe substantially equal at all speeds.

. tween .5 and 1 between the armature current and the quadrature fieldilux, and a voltage regulator lconnectable to a supply, comprisingmagnetic core means, winding means wound around said core meansconnectable to said supply, a plurality of cooperating powertransmitting means', each individually connected to the main winding,quadrature Winding or armature winding, at least one of said powertransmitting means being movable in respect to said core means toprovide variable voltages and unitary control means for moving theadjustable power transmitting means only in such a predetermined manneras to provide voltages in accordance with predetermined voltage andspeed characteristics varying for diierent speeds as to cause the speedand transformer voltages induced into the coils y undergoing commutationto be substantially magnetic core means, winding means wound around saidcore means connectable to said supply, a plurality of cooperating powertransmitting rider-means, each individually connected to the main andquadrature windings, or said armature winding and each mounted toindividually move in respect to said core means in continuous contactwith said winding means and each capable of providing an independentvariable voltage and unitary control means for simultaneously relativelymoving the adjustable rider means only in such a predetermined manner soas to provide variable voltages in accordance with predetermined voltageand speed characteristics varying for different speeds as to cause thespeed and transformer voltages induced into the coils undergoingcommutation to be substantially equal at all speeds.

7. In combination, an alternating current motor comprising statorwindings, a rotor having a coiled commutator armature winding, brushesin contact with said commutator, means to provide in the rotor a powerfactor improving component oi' voltage and a voltage regulatorconnectable to a supply, comprising magnetic core means, winding meanswound around said core means Vconnectable to said supply, a plurality ofcooperating power transmitting means, each individually connected to oneofsaid stator windings or said armature winding and each mounted toindividually move in respect to said core means and each capable ofproviding an independent variable voltage and unitary control means fOrsimultaneously relatively moving the adjustable power transmitting meansto supply voltages to said stator windings and amature winding simulsaidcoremeans and each capable of providingy an independent variable voltageand unitary control means for simultaneously relatively moving theadjustable power transmitting means to supply voltages to said statorwindingsand armature winding simultaneously substantially in accordancewith the equations e=e. and

to provide the desired output characteristics.

9. In combinuation, an alternating current motor comprising a mainwinding, a rotor having a coiled commutator armature winding, brushesplaced substantially along the axis of said main winding, a quadraturewinding spaced ninety electrical degrees from the main winding,dephasing means in the circuit of said quadrature winding comprising acapacitor of such magnitude as to dephase the circuit oi the quadraturewinding relative to that of the main winding by 'an amount to produce anangle having a cosine between .5 and 1 between the armature current' andthe quadrature field flux. and a voltage regulator connectable to asupply, comprising magnetic core means, 'winding means wound around saidcore -means connectable to said supply, a plurality of cooperating powertransmitting rider means, each individually connected t0 the mainwinding, quadrature winding or armature winding and each molmted toindividually move in respect to said core means in continuous contactwith said winding means and each capable oi providing an independentvariable voltage and unitary control means for simultaneously relativelymoving the adjustable rider means to supply voltages to said statorwindings and armature winding simultaneously substantially in accordancewith the equations et=e| and N: 1.z+ Kwis Vl to provide the desiredoutput characteristics. f

10. In combination, an alternating current motor comprising a mainwinding, a rotor hav-l ing a commutator armature winding, brushes placedsubstantially along the axis of said main winding, a quadrature windingspaced ninety electrical degrees from the main winding, means fordephasing the current in. said quadrature winding to produce an anglehaving a cosine between .5 and l between the armature current and thequadrature iield ux, and a voltage regulator connectable to a supply@comprising magnetic core means, winding means wound around said coremeans connectable to said supply, a plurality of cooperating powertransmitting rider means, each individually connected to the mainwinding,

9,199,050 taneousxy Submnuany' m accordance with the quadrature windingor amature winding and each mounted to individually move in respect tosaid core mean-sy in continuous contact with said winding means and eachcapable of providing an to provide the desired output characteristics.

1l. In combination, an alternating current motor comprising a mainwinding, a rotor having a coiled commutator armature winding, brushesplaced substantially along the axis of said main winding, a quadraturewinding spaced ninety electrical degrees from the main winding, meansfor dephasing the current in the quadrature winding to produce an anglehavinga cosine between .5 and 1 between the armature current and thequadrature neld ilux, and a voltage regulator connectable to a supply,comprising magnetic core means, winding means wound around said coremeans connectable to said supply, a plurality of i cooperating powertransmitting means, each individually connected to the main winding.quadrature winding or armature winding, at least one of said powertransmitting means being movable in respect to said core means toprovide variable voltages and unitary control means for moving theadjustablepower transmitting means to supply voltages to said mainwinding, quadrature winding and armature winding simultaneouslysubstantially in accordance with the equations ez=e| and to provide thedesired output characteristics.

12. In combination, an alternating current motor comprising a mainwinding, a rotor having a coiled commutator armature winding, aquadrature winding spaced ninety electrical degrees from the mainwinding, brushes placed substantially along' the axis of said mainwinding, means for dephasing the current in the quadrature winding toproduce an angle having a cosine between .5 and 1 between the armaturecurrent and the quadrature field flux, and a voltage regulatorconnectable to a supply, comprising magnetic core means, winding meanswound around said core means connectable to said supply, a plurality ofcooperating power transmitting rider means, each individually connectedto the main and quadrature windings or said armature winding and eachmounted to individually move in respect to said core means in continuouscontact with said winding means and each capable of providing anindependent variable voltage and unitary control means forsimultaneously relatively moving the adjustable rider means only tosupply voltages to said main winding. quadrature winding and armaturewinding simultaneously substantially in accordance with the equationse=e| and to provide the desired output characteristics.

13. In combination, a polyphase alternating current motor comprising arotor having a coiled commutator armature winding, a stator winding foreach phase, brushesy in contact with said commutator for each phase,means to provide in each rotor circuit a power factor improvingcomponent of voltage energized from other phases,

and a voltagereg'ulator connectable to a supply,l

comprising magnetic core means, winding means wound around said coremeans connectable to said supply, a plurality of cooperating -powertransmitting rider means, each individually connected to the statorwindings or the brushes for each phase and each mounted to' individuallymove in respect to said core means in continuous contact with saidwinding means and each capable of providing an independent variablevoltage and unitary control means for simultaneously relatively movingthe adjustable rider means only in such a predetermined manner as toprovide variable voltages in accordance with predetermined voltage andspeed characteristics varying for different speeds as to cause thespeedfand transformer voltages induced into the coils undergoingcommutation to be substantially equal at all speeds.

14. In combination, a polyphase alternating current motor comprising arotor having av coiled commutator armature winding, a stator winding foreach phase, brushes in contact with said commutator for each phase, anda voltage regulator connectable to a supply, comprising magnetic coremeans, winding means wound around said core means connectable to saidsupply, a

plurality of cooperating power transmitting ridermeans, eachindividually connected to the stator t windings or the brushes for eachphase and each mounted to individually move in respect to said coremeans in continuous contact with said winding means and each capable ofproviding an independent variable voltage and unitary control means forsimultaneously relatively moving the adjustable rider means only in sucha predetermined manner as to provide variable voltages in accordancewith predetermined voltage and speed characteristics varying fordifferent speeds as to cause the speed and transformer voltages inducedinto the coils undergoing commutation to be substantially equal at allspeeds. i

15. In combination, a polyphase alternating current motor comprising arotor having a coiled commutator armature winding, a stator winding foreach phase, brushes in contact with said commutator for each phase,power factor coils in each rotor circuit to provide a power factorimproving component of voltage in said rotor circuit energized fromother phases and a voltage regulator connectable to a supply, comprisingmagnetic core means, winding means wound around said core meansconnectable to said supply, a plurality of cooperating powertransmitting rider means, each individually connected to the statorwindings or the brushes for each phase, and each mounted to individuallymove in respect to said core means in continuous contact with `saidwinding means land each capable of providing an independent variablevoltage and unitary control means for simultaneously relatively movingthe adjustable rider means only in such a predetermined manner as toprovide variable voltages in accordance with predetermined voltage andspeed characteristics varying for dif-fl ferent speeds as lto cause thespeed and transformer voltages linduced into the coils undergoingcommutation to be substantially equal at all speeds.

16. In combination, a polyphase alternating current motor comprising arotor having a coiled A around said core means connectable to saidsupply, a plurality of cooperating power transmitting means, eachindividually connected to the brushes for each phase and each mounted toindividually move in respect to said core means and each capable of,providing an independent variable voltage and unitary control means forsimultaneously relatively moving the adjustable power transmitting meansonly in such a predetermined manner as to provide independent variablevoltages in 'accordance with predetermined voltage and speedcharacteristics varying for different speeds as to cause the speedandtransformer voltages induced into the coils undergoing commutation tobe substantially equal at all speeds.

17. In combination, a polyphase alternating current motor comprising arotor having a coiled `commutator armature winding, a stator windingforeach phase, brushes in contact with said commutator for each phase,means to provide in each rotor circuit a power factor improvingcomponent of voltage energized from otherVy phases, and a voltageregulator connectable to a supply, comprising vmagnetic core means,winding means wound around said core means connectable to said supply, aplurality of cooperating power transmitting rider means, eachindividually connected to the stator windings or the brushes for eachphase and each mounted to individually move in respect to said coremeans in continuous contact with said winding means and each capable ofproviding an independent variable voltage and unitary control means forsimultaneously relatively moving the adjustable rider means to supplyvoltages to said stator windings and phase brushes simultaneouslysubstantially in accordance with the equations et=es and -IaZ-i-Kflmfd:VA Kdw to provide the desired'output characteristics.

18. In combination, a polyphase alternating current motor comprising arotor having a coiled commutator armature winding, a stator winding foreach phase, brushes in contact with said commutator for each phase, anda voltage regulator connectable to a supply, comprising magnetic coremeans, winding means wound around said core meansr connectable to saidsupply, a plurality of cooperating power transmitting rider means, eachindividually connected to the stator windings or the brushes for eachphase and each mounted to individually move in respect to said coremeans in continuous contact with said winding means and each capable ofproviding an independent variable voltage'and unitary control to providethe desired output characteristics.

19. In combination, a polyphase alternating dll commutator armaturewinding, a stator winding for each phase, brushes in contact with saidcommutator for each phase, power factor coils in each rotor circuit toprovide a power factor improving component of voltage in said rotorcircuit energized from other phases, and a voltage regulator connectableto a supply, comprising magnetic core means, winding means wound aroundsaid core means connectable to said supply, a plurality oi' cooperatingpower transmitting rider means, each individually connected to thestator windings or the brushes for each phase and each mounted toindividually move in respect to said core means in continuous contactwith said winding means and each capable of providing an independentvariable voltage and unitary control means for simultaneously relativelymoving said adjustable rider means to supply voltages to said statorwindings and phase brushes simultaneously substantially ih accordancewith the equations ez: e: and

A24-Kauft V4 to provide the desired output characteristics.

20. In combination, a polyphase alternating current motor comprising arotor having a coiled commutator armature winding, a stator winding foreach phase, means for connecting each stator winding to the supply,brushes in contact with said commutator for each phase, and power factorcoils in each rotor circuit to provide a power factor improvingcomponent of voltage in said rotor circuit energized from other phases,a voltage regulator connectable to a supply, comprising magnetic coremeans, winding means wound around said core means connectable to saidsupply, a plurality of cooperating power transmitting means, eachindividually connected tothe brushes for each phase and each mounted toindividually move in respect to said core means and each capablel ofproviding an independent variable voltage and unitary control means forsimul taneously relatively moving the adjustable power transmittingmeans to supply voltages to said stator windings and phase brushessimultaneously substantially in accordancewith the equations c=ei andKq'w v to provide the desired output characteristics.

21. In combination,` an alternating current motor comprising statorwindings, a rotor having a coiled commutator armature winding, brushesin contact with said commutator, means to provide in the rotor a powerfactor improving component of voltage, and a voltage regulatorconnectable to a supply, comprising magnetic core means, winding meanswound around said core means connectable to said supply, a plurality ofcooperatingy power transmitting means, each individually connected toone of said stator windings or said armature winding, at least one ofsaid power transmitting means being movable in respect to said coremeans to provide variable voltages and unitary control means for movingthe adjustable power transmitting means only in such a predeterminedmanner as to provide variable voltages in accordance with predeterminedvoltage and speed characteristics varying for difvcurrent motorcomprising a rotor having a coiled ferent speeds as to cause the speedand transformer voltages induced into the coils undergoing commutationto be substantially equal at all speeds.

22. In combination, an alternating current motor comprising statorwindings, a rotor having a coiled commutator armature winding. brushesin contact with said commutator, and a voltage regulator connectable toa supply, comprising magnetic core means, winding means wound aroundsaid core means connectable to said supply, a plurality of cooperatingpower transmitting means, each individually connected to one of saidstator windings or said armature winding, at least one of said powertransmitting means being movable in respect to said core means toprovide variable voltages and unitary control means for moving theadjustable power transmitting means only in such a predetermined manneras to provide variable voltages in accordance with predetermined voltageand speed characteristics varying for different speeds as to cause thespeed and transformer voltages induced into the coils undergoingcommutation to be substantially equal at all speeds.

23. In combination, an alternating current motor comprising statorwindings, a rotor having a coiled commutator armature winding, brushesin contact with said commutator, means to provide in the rotor a powerfactor improving component oi' voltage and a voltage regulatorconnectable to a supply, comprising magnetic core means, winding meanswound around said core means connectable to said supply, a plurality ofcooperating power transmitting means, each individually connected to oneof said stator windings or said armature winding, at least one of saidpower transmitting means being movable in respect to said core means toprovide variable voltages and unitary control means for moving theadjustable power transmitting means to supply voltages to said statorwindings and armature winding simultaneously substantially in accordancewith the equations et=e. and

vcontrol means for moving the adjustable power transmitting means tosupply voltages to said stator windings and armature windingsimultaneously substantially in accordance with the equations e=es andN: -nZifKoMfi VA y Kdbo to provide the desired output characteristics.

AUSTIN S. NORCROSS.

